Tieths to



(.No Model.)

w. NJRIOHARDS. SELF GOAUNTERSINKING SCREW.

310465101 ,P'atentedDeo.15,1891.

T E E T- N V E T UR UNITED STATES PATENT QFFICE.

WI LIAM N. RICHARDS, or 'LYONS, NEW roamnssrenon or NINE-TWEN- TIETHS TO JOHN DQALDEN', OF sAME'PLAcE.

sELF-cou NTERSINKING" SCREW. I

I Y SPECIFICATION forming part of Letters Patent No. 465,101,'dated December 15,1891.

.- application filed December 1390. Serial No 873,644. (No model.)

,TO all whom it may concern,

of Lyons, in the county of Wayne, in the State of New York, have invented certain new-and useful Improvements in Self-Countersinking Screws, of which the following, taken in connection with the accompanying drawings, is a full, clear, and exact description.

My invention relates to that species of metallic screws commonly designated as countersinking-screws, and applicable for use in wood-Work and analogous purposes.

The object of myinvention is to produce'a screw of thecharacter mentioned, of improved and advantageous construction and insuring satisfactory and reliable operation and service, and the limitation of the projecting of the head of .the screw into the self-formed countersink in the wood farther than is desirable and concurrently insuring proper hearing therefor. Obviously, as in other devices wherein the screw is of a self-countersinking character, when my screw is screwed into wood or other operative material, it will, through the movement imparted to the stem and knife-provided head by the manipulating screw-driver, create a countersink of the exact depth requisite for the proper reception of the head of the screw, and coincidently creating a satisfactory bearing for said head.

' l\ly invention consists in the novel featuresof constructioh, details of formation, combination of theparts, and perfect adaptability for the purposes designed, as hereinafter de scribed, and clearly enumerated in the claims hereto annexed. It is constructed as follows:

A is the circumferentially-beveled head, and B the elongated stem or shank provided with the customary threads on a a, &c., said threaded stem terminating in the usual point b. Upon the under or beveled side of the screw-head A are disposed one or more knives or cutting-blades 1, projecting both obliquely and diagonally outward from the beveled side of the head, the said lateral knife or knives extending from the bottom of the beveled surface of the head to within a short distance I of its top, and the cutting blades or knives gradually taper outwardly,starting at the bottom of the beveled surface of the head and terminating at their point of greatest lateral projection, as at c, slightly below the top surface of the head and vertically lineal with the circumferential edge (1 of the horizontal surface of said screw-head, and whereby the circular top of the head of the screw will set into a countersink of similar dimensions at its upper portion, the lineal projection of the circumferential top edge 01 and project ng point of the knife or cutting blade-l being clearly shown at dotted line w 40.

By means of the afore-described upper outward projection of the knives, as at c, It s evident they will cut the strongest and deepest at the upper portion of the screw-head A, and witha lighter or more superficial cut at the bottom portion thereof, the cutting gradually becoming stronger and deeper upward as the cutting-edge incliningly diverges out ward. to its terminating point 0. I

When deemed desirable or expedient, I can form the knives 1 in such manner that they will start gradually from or about the top of the screw-head and continuing laterally outward and having their point of greatest project-ion (in relation to the beveled side of the As is apparent, the cutting-blades 1 project outwardly beyond the peripheral surface of the beveled side of the screw-head, the dis-" tance of the cutting-edge of same from the beveled side of the head gradually increasin g until its angular projecting point e is reached.

The proj ectingknives orblades 1 maybe constructed by being raised up from the beveled under side of the screw-head by cutting into same with asuitable tool or other satisfactory means, or by forming the knives on the beveled side of thehead without cutting into the metal thereof. In either case the cuttingblades are by choice integral with the screwhead. The small shavings created by the motion of the knives will pass upwardly at or alongside the top thereof in variably. ,the knives being disposed on the proper angle.

I am aware of the existence of countersinking-screws wherein their blades or cuttingknivcs extend continuously from the stem or body of the screw clear to the top of the FCICW- head, andwhieh are of no practical value or utility for the reason that such formation of the knives afford no shoulder or hearing for the head, and consequently, there virtually being no limitation to the rotation of the screw, continued turning thereof would obviously impel it entirely through a board, or, at any rate, being liable to enter both at its stem and head portionsmuch farther into the wood than desirable, except through the exercise of great caution on the part of the operator. Moreover, those forms of screws having knives extending upwardly to the very top of the head, necessarily cannot hold any better, if as well as an ordinary nail or spike, as being devoid of a shoulder portion, (as embodied by the point e of the knife in my constructiom) terminating on a lower plane than the top surface of the head and vertically lineal with its circumferential edge there is not anything for the screw-stem to work or pull against. Particularly is this apparent in the attempt of screwing two pieces of wood tightly together, the drawing of them tightly and immovably together being unat- --tainable, owing to the non-limitation of the screws turning. As is obvious, by my novel formationand arrangement oft-he cutting-blades, in connec- 'tion with the head of the screw, as embodied in my'invention, a screw of simple, durable, and inexpensive construction is provided, and wherein the defects or drawbacks incidental to the employment for service of the so-termed countersinking-screws now existent are entirely obviated,-and a perfect working and thoroughly satisfactory cou ntersinking-screw is resultant.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is- 1. A countersinking-screw provided upon the under or beveled side of its head with one or more blades diverging therefrom, whose pointof greatest projection lies beneath and apart from the circumferential smooth edgebounding the heads top, and whereby a space is created vertically between said projecting point of the blade or-bladcs and the overhead smooth boundary edge of the top of the screwhead, substantially as shown and described, and for the purposes specified.

2. A conntersinking-screw having upon the under or beveled surface of its head one or more blades standing outwardly therefrom,

whose point of greatest projection stands vertieally lineal with the circumferential boundary edge of the top of the screw-head upon a plane lying beneath the circumferential edge of the top of said head, substantially as shown and described, and for the purposes specified.

3. A countersinking-serew provided upon the under or beveled surface of its head with one or more cutting-blades or knives projecting diagonally therefrom and obliquely thereto, the pointof greatest projection of the said blade or blades standing 'erticallylineal with the circumferential boundary edge of the top of the head and terminating on a plane lying beneath the plane of the top of the screwhead, whereby a space is created between the circumferential edge of the heads top and the underlying projecting point of the blade or blades, substantially as described and shown, and for the purposes set forth.

4. A copntersinking-serevv whose head is provided at its under or beveled side with one oizmore cutting-blades of triangular form,

extending outwardly therefrom and having anangular or V-shaped projecting point lying beneath the periphery of the top of the head and in non-contact with the screw-head, substantially'as described and shown, and for the purposes set forth.' o

In testimony whereof I have hereunto signed my name and affixed my seal, in the presence of two attesting witnesses, at Syracuse, in'the county of Onondaga, in the State of New York, this 25th day of November, 1890.

WILLIAM N. RICHARDS. [n sl Witnesses: WV M. (J. RAYMOND, E.- KAUKnMoELLnn. 

